docs(prd): fold 2026-07-09 debate-pass findings into Mosaic Platform PRD

All 24 panel findings (P0#1-5, P1#6-13, P2/P3#14-24) accepted and folded:
- DEBATE-FINDINGS.md: disposition record + open-disagreement judgment calls
- north-star: NS-14, J2a/J2b split, J6 wake router, K3 push pipeline,
  M1 memory subsystem, workstream L (MALS lineage), real DAG edges
- J: workspace lease J-R16, resume protocol J-R18, write-side trust,
  needs-decision lifecycle, atomic card publish
- P: CAS approval state machine, gateway-only credentials, default-closed
  gating, principal resolution + policy snapshot (Codex #2/#7)
- W: butt-in exclusive lease, structured control plane, break-glass
  doctrine, trial metric panels
- Q: external_refs table, pending-link, echo-loop guard, crash barriers
- X: storage authority (Postgres sole record), machine-generated census,
  memory retrieval-eval retirement gate, honest rollback scope,
  4 artifact-existence machine gates, bounded day-30 review
- README: Gate Zero, conflict register, DoD line, silent-roster rule

One item OPEN for Jason at ratification: gate superstructure (§3.1).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RMoEx7hfdFGjUiCHuN1RRi

docs/fleet/proposals/mosaic-platform-prd/PRD-backlog-providers.md

@@ -1,6 +1,7 @@
 # PRD — Backlog Provider Sync Adapters · Workstream Q
 
 > **Status:** DRAFT for ratification · **Goals:** Q1–Q3 · **Doctrine:** NS-12 (ratified D3)
+> **Debate pass 2026-07-09:** panel findings folded — see `DEBATE-FINDINGS.md`.
 
 ## Mission
 
@@ -30,11 +31,22 @@ Users choose where they _see and touch_ work — Gitea, GitHub, a local kanban
 | ---- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | Q-R7 | A webUI kanban board over the native backlog (no external provider needed) — the "local kanban" choice. Builds on W3's card views and/or the existing `KanbanBoard` component upgraded from demo-grade to live data. |
 
+## Debate-accepted deltas (2026-07-09) — normative
+
+| ID    | Requirement                                                                                                                                                                                                                                                                                                                                          |
+| ----- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| Q-R8  | **External-ref linkage is one shared mechanism:** a unique-indexed `external_refs(entity_id, system, external_id)` table serves adapter linkage (Q-R1), migration idempotency (X-R4 anti-join), and re-point verification (X-R6) — built once, three consumers. Idempotent upsert; a violated unique index is a converge signal, never an overwrite. |
+| Q-R9  | **Crash-safe external creates:** the adapter writes a `pending-link` row **before** any external create and embeds a deterministic card-id marker in the created item, so a crash between create and link-back is recovered by scan, never by duplicate creation.                                                                                    |
+| Q-R10 | **Echo-loop guard:** both directions carry revision counters; adapter-authored external edits are tagged (marker/actor) and skipped on read-back. A sync cycle that would re-import its own write is a hard test failure.                                                                                                                            |
+| Q-R11 | The sync engine is a **level-triggered reconciler** over desired-vs-observed state (same doctrine as J6), not a webhook-only event chase: webhooks accelerate convergence, the reconciler guarantees it. Missed webhooks are a latency event, not a correctness event.                                                                               |
+| Q-R12 | Card spec immutability (J-R20) projects cleanly: the mirrored issue body is the pinned spec revision; amendments append as **ordered provider comments**, never body rewrites, so external watchers see the same amendment history as the native record.                                                                                             |
+
 ## Acceptance criteria
 
 1. A card created by Jarvis (J3) appears as a Gitea issue within one sync interval; closing the issue in Gitea marks the card for review, not silent closure; dispatch/claims never round-trip through Gitea.
 2. Killing the adapter mid-mission: dispatch continues unaffected (record is native); on restart, sync converges without duplicates.
 3. The same mission can be mirrored to Gitea and viewed on the local kanban simultaneously without state divergence.
+4. **Named crash barriers** at every external-call boundary (`before_external_create`, `after_create_before_link`, `after_link_before_ack`): kill the adapter at each; zero duplicate external items, zero orphaned cards. CI rule: a new external call site without a named barrier + kill test **fails the build**. Residual randomized soak is trace-directed (§3.6 disposition).
 
 ## Non-goals